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Fig. 8.34 The lichen Pleopsidium chlorophanum , which is an extremophile, collected from
Antarctica were placed inside the German Aerospace Center (Deutsches Zentrum für Luft- und
Raumfahrt - DLR)'s Mars Simulation Laboratory for 34 days. It was exposed to harsh Mars-
like conditions in the laboratory and have been found to survive, preferring to cling to cracks
in rocks and in gaps in the simulated Martian soil ( http://www.dlr.de/dlr/en/desktopdefault.aspx/
tabid-10081/151_read-3409/#/gallery/5681 - Image: DLR, CC-BY 3.0, 2012)
Archaean microfossil records (Schopf and Walter 1983 ;deMorais 2004 ), as the
Earth's stromatolites analog (Walter 1983 ;Stoker 1996 ).
When Mars' environment was wetter than today, with possible liquid water
flowing on its surface, or even small oceans (Head et al. 1999 ), perhaps it gave
opportunity for microbial life to possibly have originated within Martian subsurface
hydrothermal systems, as Earth's active Fe-S accumulations systems (Libes 1992 ),
on distant-past Mars around 3-4 Gyrs, and became fossilized, or hypothetically
is still dormant beneath possible ice-covered small lakes deep inside subsurface
Martian ice (McKay 1993 ; Mitrofanov et al. 2003 ;deMorais 2004 ), as Mars dried
up during its evolution (McKay and Stoker 1989 ; McKay et al. 1991a , b ).
On Earth, there is a place which gets somewhat close, in terms of environmental
conditions, to these possible Martian subsurface ice-covered small lakes. It is the
McMurdo Dry Valley region of southern Victoria Land in Antarctica, the largest
ice-free region of Antarctica and one of the coldest and driest deserts in the world.
There are numerous meltwater lakes in this region thanks to two regional features,
the Transantarctic Mountain Range that blocks the flow of ice from the polar plateau
and eliminates precipitation and the very low mean air temperature ( 15 to 30 ı C)
that provides perennial ice cover, 3-6 m thick, to the lakes.
“In November 2004, NIWA scientists Kay Vopel and Ian Hawes went under the
ice to measure, for the first time, the rates of photosynthesis of microbial mats
within one of the permanently ice-covered lakes of the McMurdo Dry Valleys.
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